The invention relates to the monitoring of a process performed on a substrate and detection of a property of a material on the substrate.
In substrate fabrication processes, semiconductor, dielectric, and conductor materials, such as for example, polysilicon, silicon dioxide, aluminum and or tungsten silicide, are formed on a substrate by chemical vapor deposition (CVD), physical vapor deposition (PVD), and oxidation and nitridation processes; and the substrate may also be implanted with ions or etched in an etching process. In a typical CVD process, a reactive gas is used to deposit material on the substrate, and in a PVD process, a target is sputtered to deposit material on the substrate. In oxidation and nitridation processes, an oxide or nitride material, such as silicon dioxide or silicon nitride, respectively, is formed on the substrate by exposing the substrate to a suitable gaseous environment. In subsequent etching processes, a patterned etch resistant mask of photoresist or oxide hard mask is formed on the substrate by lithographic methods, and the exposed portions of the substrate are typically etched by an energized gas to form patterns of gates, vias, contact holes or interconnect lines.
In such processes, it is often desirable to use a process monitoring method to control processing of the substrate at predetermined stages or endpoint times. For example, in the etching of gate structures, it may be desirable to stop etching of overlying polysilicon as soon as the underlying dielectric is reached. However, the dielectric is often a thin layer which makes it difficult to etch through the overlying polysilicon without etching through the dielectric. As another example, it is desirable to stop etching when the dielectric is etched through or etched slightly beyond its thickness (a small depth into the underlying material) to ensure removal of all of the dielectric material. As a further example, it may be desirable to stop a deposition, oxidation or nitridation process when a predetermined thickness of material is obtained.
Typical process monitoring methods detect radiation in the chamber to monitor the process and determine a process endpoint. These methods include, for example, plasma emission analysis in which an emission spectrum of a plasma in the chamber is analyzed to determine a spectral change that arises from a change in the material being etchedxe2x80x94which may occur upon etching through a materialxe2x80x94as for example taught in U.S. Pat. No. 4,328,068 which is incorporated herein by reference. In another example, U.S. Pat. No. 5,362,256, which is also incorporated herein by reference, discloses a method of monitoring a process by monitoring a plasma emission intensity at a selected wavelength and correlating variations in the intensity with a process endpoint. In another method called ellipsometry, a polarized light beam reflected from a surface of a material being etched is analyzed to determine a phase shift and magnitude of the reflected beam, as for example disclosed in U.S. Pat. Nos. 3,874,797 and 3,824,017, both of which are incorporated herein by reference. In interferometry, a beam reflected from a material being processed is monitored to determine etch depth by counting maxima and minima in the reflectance signal or from cessation of the signal, as for example disclosed in U.S. Pat. No. 4,618,262 to Maydan et al, which is also incorporated herein by reference. While these process monitoring methods are useful to detect a process endpoint, they do not provide information on the stage of a process or a property of the material being processed.
It is desirable to have a process monitoring method capable of detecting a change in a property of a material being processed on a substrate. It is further desirable to have an apparatus capable of detecting etch through or a deposition endpoint of a layer being formed on the substrate. It is also desirable to have a process monitoring system capable of quantitatively measuring the property, such as the thickness of a material being processed on the substrate.
The present invention is capable of satisfying these needs by allowing monitoring of a substrate fabrication process to detect a process stage or a property of a material on the substrate. In one aspect, the present invention comprises a substrate processing apparatus comprising a process chamber capable of processing a substrate. A radiation source is capable of providing non-polarized radiation that is at least partially reflected from a substrate in the chamber. A radiation detector is provided to detect the reflected radiation and generate a signal. A controller is adapted to receive the signal and determine a property of a material on the substrate in the chamber.
In one version, the apparatus comprises a computer having a memory capable of operating a computer-readable program embodied on a computer-readable medium, the computer readable program including program code to receive the signal and determine a property of the material on the substrate in the chamber.
In another aspect, the present invention relates to a method of processing a substrate, in which, the substrate is placed in a process zone, and process conditions are set in the process zone to process the substrate. Non-polarized radiation reflected from the substrate is detected before, after, or during processing of the substrate. The detected radiation is evaluated to determine a property of a material on the substrate in the chamber.
In another aspect, an apparatus comprises a process chamber capable of processing a substrate and a radiation source capable of providing radiation that is at least partially reflected from the substrate during processing. A radiation detector is provided to detect the reflected radiation and generate a signal. A controller is adapted to receive the signal and determine both an onset and a completion of processing of a material on the substrate.
In one version, the apparatus comprises a computer having a memory capable of operating a computer-readable program embodied on a computer-readable medium, the computer readable program including program code to receive a signal from the radiation detector and to detect both an onset and completion of processing of a material on the substrate.
In another aspect, a method of processing a substrate, in which, the substrate is placed in a process zone, and process conditions are set in the process zone to process the substrate. Radiation reflected from the substrate is detected, and both an onset and completion of processing of a material on the substrate may be determined.
In another aspect, an apparatus comprises a process chamber capable of processing a substrate in a plasma. One or more radiation detectors are provided to detect a radiation emission from the plasma and generate a first signal, and to detect a radiation reflected from the substrate and generate a second signal. A controller is adapted to receive the first and second signals.
In one version, the apparatus comprises a computer having a memory capable of operating a computer-readable program embodied on a computer-readable medium, the computer readable program including program code to receive the first and second signals and determine an event in the chamber or a property of a material on the substrate.
In another aspect, a method of processing a substrate, in which, the substrate is placed in the process zone, and process conditions are set to form a plasma to process the substrate. A radiation emission from the plasma is detected and a first signal is generated. A radiation reflected from the substrate is also detected and a second signal is generated. The first and second signals are evaluated to determine the occurrence of an event in the process zone or a property of a material on the substrate.
In another aspect the apparatus comprises a chamber capable of processing a substrate, a radiation source capable of providing radiation that is at least partially reflected from a substrate in the chamber, a radiation detector adapted to detect the reflected radiation and generate a signal, and a controller adapted to receive the signal and determine the thickness of, or the dopant level in, a material on the substrate.
In one version, the apparatus comprises a computer having a memory capable of operating a computer-readable program embodied on a computer-readable medium, the computer readable program including program code to receive the signal and determine the thickness of, or the dopant level in, a material on the substrate.
In another aspect, a method of processing a substrate in which the substrate is placed in a process zone, radiation reflected from the substrate before, during, or after processing of the substrate in the process zone is detected, and the detected radiation is evaluated to determine the thickness of, or the dopant level in, a material on the substrate.
In another aspect, the apparatus comprises a chamber capable of processing a substrate, a radiation source capable of providing radiation that is at least partially reflected from a substrate in the chamber, a radiation detector adapted to detect the reflected radiation and generate a signal, and a controller adapted to receive the signal and evaluate an amplitude change of the reflected radiation in relation to a calculated or stored range of amplitude changes for a batch of substrates.
In another aspect, a method comprising the steps of placing a substrate in the process zone, detecting radiation reflected from the substrate before, during, or after processing of the substrate in the process zone, and evaluating an amplitude change of the reflected radiation relative to a calculated or stored range of amplitude changes for a batch of substrates.
In another aspect, the apparatus comprises a chamber capable of processing a substrate, a radiation source capable of providing radiation that is at least partially reflected from a substrate in the chamber, a radiation detector adapted to detect the reflected radiation and generate a signal, and a computer having a memory capable of operating a computer-readable program embodied on a computer-readable medium, the computer readable program including program code to receive the signal and evaluate an amplitude change of the reflected radiation in relation to a range of amplitude changes for a batch of substrates.
In another version, the apparatus comprising a chamber capable of processing a substrate, a radiation source capable of providing radiation that is at least partially reflected from a substrate in the chamber, a radiation detector adapted to detect the reflected radiation and generate a signal, and a controller adapted to receive the signal and evaluate the signal to determine if a thickness of an insulator on the substrate is sufficiently large to reduce electrical breakdown through the insulator.
In another aspect, a method comprising the steps of placing the substrate in the process zone, detecting radiation reflected from the substrate before, during, or after processing of the substrate in the process zone, and evaluating the reflected radiation to determine if a thickness of an insulator on the substrate is sufficiently large to reduce a possibility of electrical breakdown through the insulator.
In another aspect, the apparatus comprises a chamber capable of processing a substrate, a radiation source capable of providing radiation that is at least partially reflected from a substrate in the chamber, a radiation detector adapted to detect the reflected radiation and generate a signal, and means for evaluating the signal to determine a thickness of an insulator on the substrate before completion of processing.
In another aspect, the apparatus comprises a chamber capable of processing a substrate, a radiation source capable of providing radiation that is at least partially reflected from a substrate in the chamber, a radiation detector adapted to detect the reflected radiation and generate a signal, a controller adapted to receive the signal and generate a set of data relating to a property of the substrate, and a factory automation host computer to receive the data.